1. Field of the Invention
This invention relates generally to motor vehicle powertrains that are sometimes referred to as hybrid powertrains. Such a hybrid powertrain comprises an internal combustion (I.C.) engine and a rotary electric machine arranged to operate in various modes for more efficiently operating a motor vehicle powertrain. The rotary electric machine is capable of operating alternately as an electric motor and as an electric generator, or alternator.
2. Background Information
The state of the art is reflected in the following pending patent applications of the inventor:
The present invention relates to novel hybrid powertrains and methods of making such powertrains. The invention is especially adapted for a powertrain that can operate a vehicle solely by a rotary electric machine operating as a source of powertrain torque (i.e. as an electric motor), solely by an I.C. engine as a source of powertrain torque, or by a combination of the two. When there is a demand for driveline torque that cannot be met solely by the engine, the rotary electric machine can operate as an electric motor to make an added positive torque contribution to the vehicle driveline. When the engine is essentially meeting driveline torque demand, the rotary electric machine can smooth the pulsating engine crankshaft torque that occurs when the engine lacks a torque damper such as a flywheel. Torque smoothing is achieved by operating the rotary electric machine alternately as a motor and as a generator to make alternate small positive and negative contributions to powertrain torque for attenuating, at least to some degree, the pulsations in engine crankshaft torque.
Because the rotary electric machine is capable of operating as an electric generator, it can sink, i.e. extract, kinetic energy from the powertrain by converting that energy into electricity for re-charging an on-board electric storage medium, such as a battery. Conversion of kinetic energy from the running engine into electric energy for powering the vehicle electrical system can render the engine-driven alternator that is present in a non-hybrid vehicle potentially redundant, and therefore unnecessary, in a hybrid vehicle embodying the present invention. When the transmission is momentarily disengaged from the engine during a transmission gear change, particularly an upshift, kinetic energy may be extracted from the running engine to improve shift quality by more quickly changing crankshaft speed. When the energy that the rotary electric machine converts into electricity comes from kinetic energy of the moving vehicle, rather than the engine, the recovered energy serves to improve vehicle operating efficiency.
Because the rotary electric machine is capable of operating as an electric motor, it can be used to crank the engine at engine starting. Hence, the separate electric starter motor present in a non-hybrid vehicle may be redundant, and therefore unnecessary, in a hybrid vehicle embodying the present invention.
One generic aspect of the invention relates to a method of making a motor vehicle powertrain comprising an internal combustion engine having a crankshaft coupled to a transmission through an assembly comprising a rotary electric machine and a clutch through which the crankshaft can be selectively engaged with and disengaged from the assembly. The rotary electric machine comprises a stator and a rotor that are separated by a radial air gap, and the rotary electric machine is selectively operable as an electric motor to source torque to the powertrain and as an electric generator, or alternator, to sink torque from the powertrain. The sourcing of torque to the powertrain and the sinking of torque from the powertrain may occur in any of the several ways mentioned earlier.
The method comprises assembling a ring that comprises a circular pilot surface to a face of the engine in surrounding relation to the crankshaft to establish concentricity of the circular pilot surface to an axis of rotation of the crankshaft; assembling the stator to the face of the engine to establish concentricity of the stator to the axis of rotation of the crankshaft; assembling the rotor into the powertrain, including piloting a circular pilot surface of an engine side bracket that is disposed over an engine side of the rotor facing the engine to the circular pilot surface of the ring via an engine side bearing assembly to establish concentricity of the engine side of the rotor to the crankshaft axis; coupling an output of the clutch to a transmission side bracket that has a circular pilot surface to couple the transmission side bracket and output of the clutch for rotation in unison; assembling the coupled clutch and transmission side bracket into the powertrain by disposing the clutch within a space surrounded by the rotor and coupling an input of the clutch to the crankshaft to couple the clutch input and the crankshaft for rotation in unison, and disposing the transmission side bracket over a transmission side of the rotor that is opposite the engine side; fastening the two brackets and the rotor for rotation in unison about the crankshaft axis of rotation; and assembling the transmission into the powertrain including the steps of establishing a coupling of the input of the transmission to the output of he clutch to couple the transmission input and the clutch output for rotation in unison about the crankshaft axis of rotation, of piloting a first circular pilot surface of the transmission that is concentric with the transmission input to the circular pilot surface of the stator, and establishing concentricity of the transmission side bracket to the transmission through a transmission side bearing assembly disposed between the pilot surface of the transmission side bracket and a second circular pilot surface of the transmission that is concentric with the transmission input.
Another aspect relates to a motor vehicle powertrain comprising an internal combustion engine having a crankshaft coupled to a transmission through an assembly comprising a rotary electric machine and a clutch through which the crankshaft can be selectively engaged with and disengaged from the assembly. The rotary electric machine comprises a stator and a rotor that are separated by a radial air gap, and the rotary electric machine is selectively operable as an electric motor to source torque to the powertrain and as an electric generator, or alternator, to sink torque from the powertrain. The sourcing of torque to the powertrain and the sinking of torque from the powertrain may occur in any of the several ways mentioned earlier.
The stator is assembled to the face of the engine to establish concentricity of the stator to the axis of rotation of the crankshaft. A circular pilot surface is disposed on a face of the engine in surrounding relation to the crankshaft and concentric with the crankshaft. An engine side bracket is disposed over an engine side of the rotor facing the engine and comprises a circular pilot surface. A transmission side bracket is disposed over a transmission side of the rotor opposite the engine side and comprises a circular pilot surface. The transmission side bracket and an input of the transmission are coupled together for rotation in unison. Fasteners fasten the two brackets and the rotor together for rotation in unison about the crankshaft axis of rotation with the circular pilot surfaces of the two brackets concentric. A clutch is disposed within a space surrounded by the rotor and comprises an input coupled to the crankshaft for rotation in unison with the crankshaft and an output coupled to the transmission side bracket for rotation in unison with the transmission side bracket, and hence also with the transmission input. An engine side bearing assembly comprises inner and outer races. One of the races is piloted on the circular pilot surface on the engine surrounding the crankshaft and the other of the races is piloted on the circular pilot surface of the engine side bracket to establish concentricity of the engine side of the rotor to the axis of rotation of the crankshaft. A transmission side bearing assembly comprises inner and outer races. One of the races of the transmission side bearing assembly is piloted on a circular pilot surface of the transmission that is concentric with the transmission input and the other of the races is piloted on the circular pilot surface of the transmission side bracket.
Still another aspect relates to a motor vehicle powertrain comprising an internal combustion engine having a crankshaft that rotates about an axis of rotation and that is coupled to a transmission through an assembly comprising a rotary electric machine and an engine disconnect clutch. The rotary electric machine comprises a stator and a rotor that are separated by a radial air gap concentric to the axis of rotation of the crankshaft, and the rotary electric machine is selectively operable as an electric motor to source torque to the powertrain and as an electric generator to sink torque from the powertrain. An engine side bracket is disposed over an engine side of the rotor facing the engine and a transmission side bracket is disposed over a transmission side of the rotor opposite the engine side. The two brackets are fastened together to clamp the rotor between them. The clutch is disposed within a space surrounded by the rotor and comprises an input coupled to the crankshaft for rotation in unison with the crankshaft and an output coupled to the transmission side bracket and the transmission input for rotation in unison with the transmission side bracket and the transmission input. The coupling of the clutch input to the crankshaft provides axial lost-motion that does not interfere with axial play of the crankshaft relative to the engine. An engine side bearing assembly comprises inner and outer races. One of the races is piloted on a circular pilot surface on the engine surrounding the crankshaft and the other of the races is piloted on a circular pilot surface of the engine side bracket to establish concentricity of the engine side of the rotor to the axis of rotation of the crankshaft. A transmission side bearing assembly comprises inner and outer races. One of the races of the transmission side bearing assembly is piloted on a circular pilot surface of the transmission that is concentric with the transmission input and the other of the races is piloted on a circular pilot surface of the transmission side bracket. The bearing assemblies axially capture the brackets and rotor while providing axial lost-motion play of the brackets and rotor relative to the bearing assemblies to allow the rotor to position itself axially with respect to the magnetic field of the stator for most efficient operation.
Still another aspect relates to a motor vehicle powertrain comprising an internal combustion engine having a crankshaft that rotates about an axis of rotation and that is coupled to a transmission through an assembly comprising a rotary electric machine and an engine disconnect clutch. The rotary electric machine comprises a stator and a rotor that are separated by a radial air gap concentric to the axis of rotation of the crankshaft, and the rotary electric machine is selectively operable as an electric motor to source torque to the powertrain and as an electric generator to sink torque from the powertrain. The clutch comprises an input that rotates in unison with the crankshaft and an output that rotates in unison with the rotor. The rotor is supported for rotation concentric with the axis of rotation of the crankshaft. An engine side bracket is disposed over an engine side of the rotor facing the engine. A transmission side bracket is disposed over a transmission side of the rotor opposite the engine side and coupled with an input of the transmission for rotation in unison with the transmission input. Each bracket comprises a respective circular pilot surface. Fasteners fasten the two brackets and the rotor together for rotation in unison and with the circular pilot surfaces of the two brackets concentric. The clutch is disposed within a space surrounded by the rotor and comprises an input coupled to the crankshaft for rotation in unison with the crankshaft and an output coupled to the transmission side bracket for rotation in unison with the transmission side bracket, and hence with the transmission input. The rotor is supported for rotation by an engine side bearing assembly comprising inner and outer races, wherein one of the races is piloted on a circular pilot surface on the engine surrounding the crankshaft and the other of the races is piloted on the circular pilot surface of the engine side bracket to establish concentricity of the engine side of the rotor to the axis of rotation of the crankshaft, and by a transmission side bearing assembly comprising inner and outer races, wherein one of the races of the transmission side bearing assembly is piloted on a circular pilot surface of the transmission that is concentric with the transmission input and the other of the races is piloted on the circular pilot surface of the transmission side bracket. The pilot surface of each bracket comprises an adjacent concentric groove containing an O-ring having a periphery protruding from the groove, and one race of each bearing assembly is interference fit to the protruding periphery of the respective O-ring. Each O-ring is asymmetric, in the axial direction, to a respective set of bearing elements captured between the races of the respective bearing assembly.
Still another aspect relates to a motor vehicle powertrain comprising an internal combustion engine having a crankshaft that rotates about an axis of rotation and that is coupled to a transmission through an assembly comprising a rotary electric machine and an engine disconnect clutch. The rotary electric machine comprises a stator and a rotor that are separated by a radial air gap concentric to the axis of rotation of the crankshaft, and the rotary electric machine is selectively operable as an electric motor to source torque to the powertrain and as an electric generator to sink torque from the powertrain. The clutch comprises an input that rotates in unison with the crankshaft and an output that rotates in unison with the rotor. A single sensor comprising dual sensing elements is disposed such that a first sensing element can sense crankshaft rotation and a second sensing element can sense rotor rotation.
Further aspects will be seen in various features of a presently preferred embodiment of the invention that will be described in detail.